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LeanPool.RareSubtreePatterns.Extremes.MaxString

Theorem thm:max_string: the maximal complete non-fringe r-ary height #

Source lines 475–521 (statement), 2800–2897 (proof, inventory P20). The target is the reviewed statement PoissonDeclumping.MaxStringStatement of Statements/Main.lean. The final theorem maxString_of takes Theorems thm:PoissonApproximation and thm:PoissonApproximation2 as hypotheses of exactly their reviewed statement types (PoissonApproximationStatement, PoissonApproximation2Statement); everything else is proved from the hypothesis InStableDomain μ (through Stable.stableToolkit).

All marks are G_k = 1{H_{r,k} ≺ ·} (Embeds (completeTree r k)), with π_k = μ_1^k (r = 1) or μ_r^{(r^k-1)/(r-1)} (r ≥ 2), and the cutoff is M_n = max 1 ⌊n^{1-η}⌋₊ with η = (1 - 1/α)/2 (correction F11). All limits run along admissible sizes.

theorem PoissonDeclumping.Extremes.cB_ne_one {μ : PMF ℕ} (hc : IsCritical μ) :
cB μ {d : ℕ | d ≠ 1} = 1 - μ 1

c_B = 1 - μ_1 for B = {d | d ≠ 1} (criticality: ∑ j μ_j = 1).

theorem PoissonDeclumping.Extremes.pmf_toReal_mem_Ioo {μ : PMF ℕ} {r : ℕ} (h0 : 0 < μ r) (h1 : μ r ≠ 1) :
0 < (μ r).toReal ∧ (μ r).toReal < 1

0 < μ_r < 1 in real form, for μ_r > 0 and μ_r ≠ 1.

Propagation for the unary marks: if a child of a vertex of outdegree 1 carries a unary chain of height k, so does the vertex.

theorem PoissonDeclumping.Extremes.cutoff_exponent {μ : PMF ℕ} {α : ℝ} {a : ℕ → ℝ} (hT : StableToolkit μ α a) :
(0 < (1 - 1 / α) / 2 ∧ (1 - 1 / α) / 2 < 1 - 1 / α) ∧ (1 - 1 / α) / 2 < 1

The cutoff exponent η = (1 - 1/α)/2 ∈ (0, 1 - 1/α).

{H_r(T) ≤ m} = {N_{(m+1).toNat}(T) = 0} for every integer m (r ≥ 1).

Theorem thm:max_string(i) (source lines 477–485, proof 2808–2850), conditional on Theorem thm:PoissonApproximation2 (PoissonApproximation2Statement, its part (i)).

Theorem thm:max_string(ii): thresholds #

{H_r(T) ≥ k} = {N_k(T) ≥ 1} (r ≥ 1), in the real form used by Lemma lem:ineqs.

theorem PoissonDeclumping.Extremes.tendsto_le_maxCompleteHeight_zero {μ : PMF ℕ} {α : ℝ} {a : ℕ → ℝ} (hT : StableToolkit μ α a) {r : ℕ} (hr : 2 ≤ r) {k : ℕ → ℕ} (hk : ∀ (δ : ℝ), 0 < δ → ∀ᶠ (n : ℕ) in admissibleSizes μ, ↑r ^ k n ≤ ↑n ^ δ) (hπ : Filter.Tendsto (fun (n : ℕ) => ↑n * markProb μ (fun (j : ℕ) => (PlaneTree.completeTree r j).Embeds) k n) (admissibleSizes μ) (nhds 0)) :

Upper threshold (first implication of eq:threshold_rary, source lines 2860–2872): if r^{k_n} = n^{o(1)} and n π_{k_n} → 0 along admissible sizes, then P(H_r(𝒯^n) ≥ k_n) → 0. Lemma lem:ineqs (first half, Markov) with E[N_{k_n}(𝒯^n)] ∼ n π_{k_n} (Lemma lem:S_rary(i) and Corollary cor:SM(ii)).

theorem PoissonDeclumping.Extremes.tendsto_le_maxCompleteHeight_one (h1 : PoissonApproximationStatement) {μ : PMF ℕ} (hμ : InStableDomain μ) {α : ℝ} {a : ℕ → ℝ} (hT : StableToolkit μ α a) {r : ℕ} (hr : 2 ≤ r) (hμr : 0 < μ r) {k : ℕ → ℕ} (hk : ∀ (δ : ℝ), 0 < δ → ∀ᶠ (n : ℕ) in admissibleSizes μ, ↑r ^ k n ≤ ↑n ^ δ) (hπ : Filter.Tendsto (fun (n : ℕ) => ↑n * markProb μ (fun (j : ℕ) => (PlaneTree.completeTree r j).Embeds) k n) (admissibleSizes μ) Filter.atTop) :

Lower threshold (second implication of eq:threshold_rary, source lines 2860–2872, with correction F8): if μ_r > 0, r^{k_n} = n^{o(1)} and n π_{k_n} → ∞ along admissible sizes, then P(H_r(𝒯^n) ≥ k_n) → 1. Assumption (M) comes from (S) (Lemma lem:S_rary(i) and Corollary cor:SM(i)), Assumption (C) from the summed pair bound (Lemma lem:S_rary(ii)), and N_{k_n}(𝒯^n) → ∞ in probability from Theorem thm:PoissonApproximation(ii).

theorem PoissonDeclumping.Extremes.tendsto_diff_one {μ : PMF ℕ} {E F : ℕ → Set PlaneTree} (hE : Filter.Tendsto (fun (n : ℕ) => (PlaneTree.conditioned μ n).real (E n)) (admissibleSizes μ) (nhds 1)) (hF : Filter.Tendsto (fun (n : ℕ) => (PlaneTree.conditioned μ n).real (F n)) (admissibleSizes μ) (nhds 0)) :
Filter.Tendsto (fun (n : ℕ) => (PlaneTree.conditioned μ n).real (E n \ F n)) (admissibleSizes μ) (nhds 1)

Localization from two thresholds: if P(E_n) → 1 and P(F_n) → 0 along admissible sizes, then P(E_n \ F_n) → 1.

Theorem thm:max_string(ii) (source lines 486–501, proof 2851–2897), conditional on Theorem thm:PoissonApproximation (PoissonApproximationStatement, its part (ii)), which replaces the paper's citation of Corollary cor:Non-fringe Poisson(ii) (correction F8).

Theorem thm:max_string (source lines 475–501), conditional on Theorems thm:PoissonApproximation and thm:PoissonApproximation2 (the reviewed statements PoissonApproximationStatement and PoissonApproximation2Statement).